Digital camera modules are currently being incorporated into a variety of host devices. Such host devices include cellular telephones, personal data assistants (PDAs), computers, and so forth. Consumer demand for digital camera modules in host devices continues to grow.
Host device manufacturers prefer digital camera modules to be small, so that they can be incorporated into the host device without increasing the overall size of the host device. Further, there is an increasing demand for cameras in host devices to have higher-performance characteristics. One such characteristic that many higher-performance cameras (e.g., standalone digital still cameras) have is the ability to vary the focal length of the camera to increase and decrease the magnification of the image, typically accomplished with a zoom lens, now known as optical zooming. Optically zooming is typically accomplished by mechanically moving lens elements relative to each other, and thus such zoom lenses are typically more expensive, larger, and less reliable than fixed focal length lenses. An alternative approach for approximating this zoom effect is achieved with what is known as digital zooming. With digital zooming, instead of varying the focal length of the lens, a processor in the camera crops the image and interpolates between the pixels of the captured image to create a “magnified but lower-resolution image. There have been some attempts to use two different lenses to approximate the effect of a zoom lens. It has been done in the past with film cameras in which the user could select one of two different focal lengths to capture an image on film. More recently, a variation on this concept with camera modules has been disclosed in U.S. Pat. Pub. No. 2008/0030592, the entire contents of which are incorporated herein by reference, which discusses a camera module with a pair of sensors, each having a separate lens through which light is directed to the respective sensor. In this publication, the two sensors are operated simultaneously to capture an image. The respective lenses have different focal lengths, so even though each lens/sensor combination is aligned to look in the same direction, each will capture an image of the same subject but with two different fields of view. The images are then stitched together to form a composite image, with the central portion of the composite image being formed by the relatively higher-resolution image taken by the lens/sensor combination with the longer focal length and the peripheral portion of the composite image being formed by a peripheral portion of the relatively lower-resolution image taken by the lens/sensor combination with the shorter focal length. The user selects a desired amount of zoom and the composite image is used to interpolate values therefrom to provide an image with the desired amount of zoom. Unfortunately, the disclosure in this publication is largely conceptual and lacks in certain details that would be needed to provide optimal performance.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.